Microbial stress tolerance characterization for plant-growth promotion in degraded soils

Overview

This research focuses on characterizing root-associated microorganisms isolated from serpentine soils, which are naturally nutrient-poor, drought-prone, and enriched in heavy metals such as nickel. The central hypothesis is that microbes thriving in these degraded environments possess unique genetic and physiological traits that enable them to tolerate stress and deliver plant-growth-promoting benefits under harsh conditions. By isolating, phenotyping, and whole-genome sequencing these microorganisms, the project aims to identify specific genes linked to stress tolerance and plant-growth promotion, ultimately supporting the development of microbial inoculants for crops grown in marginal or degraded soils.

Technical specifications

• Isolation and tolerance screening: Microbial isolates from serpentine and non-serpentine soils are cultured on media with and without nickel to assess heavy-metal tolerance. Serpentine-derived isolates tolerate elevated nickel concentrations, while non-serpentine isolates do not.
• Whole-genome sequencing: Genomes of microbes from both soil types will be sequenced to identify genes associated with stress tolerance and plant-growth-promoting traits.
• Functional assays: Auxin production is measured using Salkowski's reagent, phosphorus solubilization is assessed on Pikovskaya's agar, and drought tolerance is evaluated by monitoring microbial growth in the presence of PEG 6000.
• Root development imaging: A single isolate is inoculated into sterile Murashige and Skoog medium, with and without nickel, and root development is imaged weekly to observe plant-growth-promoting effects.
• Field and greenhouse foundation: Prior field surveys and two greenhouse experiments manipulating soil communities established that serpentine-derived microorganisms are necessary for seedling establishment and that plants specifically associate with a free-living nitrogen fixer on serpentine soils.

Technology readiness level

The research is at an early-to-mid stage of development. Laboratory validation has demonstrated that serpentine-derived microbial isolates tolerate elevated heavy-metal concentrations, while data analysis is ongoing. Future validation steps include whole-genome sequencing, correlation of genetic differences with functional plant-growth-promoting traits, and controlled inoculation experiments to measure root development. The project is positioned to move from phenotypic characterization toward genetic and functional validation, laying the groundwork for future development of microbial inoculants tailored for degraded soil environments.